Method and apparatus for recording information on optical disc

ABSTRACT

An optical disc of a recordable type or a rewritable type has a plurality of recording layers including first and second recording layers. A laser beam is applied to the second recording layer through a used area in the first recording layer to record arbitrary information on at least a part of the second recording layer. The used area in the first recording layer has been used for at least one of information recording and data recording. Positional information is generated. The generated positional information is of a blank area in the second recording layer which occurs due to the presence of an unused area in the first recording layer. The blank area adjoins the unused area. The generated positional information is recorded on a predetermined area in the optical disc.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method and an apparatus for recordinginformation on an optical disc such as a recordable or rewritableoptical disc. In addition, this invention relates to a computer programfor recording information on an optical disc. Furthermore, thisinvention relates to an optical disc.

2. Description of the Related Art

In a digital versatile disc recordable (DVD-R), new information can notbe written over old information or previously-recorded information.Thus, new information is written on an unused area of the DVD-R whileold information remains recorded on a used area thereof. The unused areameans an area on which data is not recorded. The used area means adata-recorded area, that is, an area on which data has been recorded.

During the recording of main information on a DVD-R, managementinformation is recorded and reproduced from the DVD-R to manage a usedarea and an unused area thereof.

DVD-Rs are of a few types including a single-layer single-sided type anda two-layer single-sided type.

Japanese patent application publication number P2002-352522A(corresponding to U.S. patent application publication numberUS-2002-136134-A1) discloses a typical prior-art apparatus for recordinginformation on a DVD-R. The prior-art apparatus in Japanese applicationP2002-352522A is designed for a DVD-R having only one recording layer.In an assumed case where the prior-art apparatus is applied to atwo-layer single-sided DVD-R, it may take a long time to search for ablank area at the time of closing a border in the DVD-R or finalizingthe data recording thereon.

In addition, Japanese application P2002-352522A discloses a method ofrecording information on a DVD-R which is designed to enhance thereliability of data representative of recording management information.According to Japanese application P2002-352522A, data containing a firstsync signal is recorded on the DVD-R and a second sync signal isrecorded thereon by cutting beforehand. The method has (a) a step ofrecording the management information on a prescribed position in theDVD-R on the basis of the first sync signal, (b) a step of decidingwhether or not the recording by the step (a) has been normally finished,and (c) a step of recording the management information on the prescribedposition in the DVD-R on the basis of the second sync signal when thestep (b) decides that the recording by the step (a) has not beennormally finished.

SUMMARY OF THE INVENTION

It is a first object of this invention to provide an apparatus forrecording information on an optical disc which can shorten a time takento close borders in the optical disc and to finalize the data recordingthereon.

It is a second object of this invention to provide a method of recordinginformation on an optical disc which can shorten a time taken to closeborders in the optical disc and to finalize the data recording thereon.

It is a third object of this invention to provide a computer program forrecording information on an optical disc which can shorten a time takento close borders in the optical disc and to finalize the data recordingthereon.

It is a fourth object of this invention to provide an improved opticaldisc.

A first aspect of this invention provides an apparatus for recordinginformation on an optical disc having a plurality of recording layersincluding first and second recording layers, the optical disc being ofone of a recordable type and a rewritable type. The apparatus comprisesfirst means for applying a laser beam to the second recording layerthrough a used area in the first recording layer to record arbitraryinformation on at least a part of the second recording layer, whereinthe used area in the first recording layer has been used for at leastone of information recording and data recording; second means forgenerating positional information of a blank area in the secondrecording layer which occurs due to the presence of an unused area inthe first recording layer, the blank area adjoining the unused area; andthird means for recording the positional information generated by thesecond means on a predetermined area in the optical disc.

A second aspect of this invention is based on the first aspect thereof,and provides an apparatus further comprising fourth means provided inthe second means for generating positional information includingpositional information pieces of one or more blank areas inclusive offirst and second blank areas in the second recording layer which occurdue to the presence of first and second unused areas in the firstrecording layer respectively, the first and second blank areas adjoiningthe first and second unused areas respectively; a memory for storing thepositional information generated by the fourth means; fifth means forrecording an arbitrary information signal on the first unused area tochange the first unused area to a used area; sixth means for recording apredetermined signal on the first blank area to change the first blankarea to a used area after the fifth means records the arbitraryinformation signal on the first unused area; seventh means for deletingthe positional information piece of the first blank area from thepositional information in the memory to update the positionalinformation; and eighth means for recording the updated positionalinformation generated by the seventh means on the predetermined area inthe optical disc.

A third aspect of this invention provides a method of recordinginformation on an optical disc having a plurality of recording layersincluding first and second recording layers, the optical disc being ofone of a recordable type and a rewritable type. The method comprises thesteps of applying a laser beam to the second recording layer through aused area in the first recording layer to record arbitrary informationon at least a part of the second recording layer, wherein the used areain the first recording layer has been used for at least one ofinformation recording and data recording; generating positionalinformation of a blank area in the second recording layer which occursdue to the presence of an unused area in the first recording layer, theblank area adjoining the unused area; and recording the generatedpositional information on a predetermined area in the optical disc.

A fourth aspect of this invention is based on the third aspect thereof,and provides a method wherein the positional-information generating stepcomprises generating positional information including positionalinformation pieces of one or more blank areas inclusive of first andsecond blank areas in the second recording layer which occur due to thepresence of first and second unused areas in the first recording layerrespectively, the first and second blank areas adjoining the first andsecond unused areas respectively. The method further comprises the stepsof storing the generated positional information in a memory; recordingan arbitrary information signal on the first unused area to change thefirst unused area to a used area; recording a predetermined signal onthe first blank area to change the first blank area to a used area afterthe arbitrary information signal is recorded on the first unused area;deleting the positional information piece of the first blank area fromthe positional information in the memory to update the positionalinformation; and recording the updated positional information on thepredetermined area in the optical disc.

A fifth aspect of this invention provides a computer program forrecording information on an optical disc having a plurality of recordinglayers including first and second recording layers, the optical discbeing of one of a recordable type and a rewritable type. The computerprogram enables a computer system to execute the steps of applying alaser beam to the second recording layer through a used area in thefirst recording layer to record arbitrary information on at least a partof the second recording layer, wherein the used area in the firstrecording layer has been used for at least one of information recordingand data recording; generating positional information of a blank area inthe second recording layer which occurs due to the presence of an unusedarea in the first recording layer, the blank area adjoining the unusedarea; and recording the generated positional information on apredetermined area in the optical disc.

A sixth aspect of this invention is based on the fifth aspect thereof,and provides a computer program wherein the positional-informationgenerating step comprises generating positional information includingpositional information pieces of one or more blank areas inclusive offirst and second blank areas in the second recording layer which occurdue to the presence of first and second unused areas in the firstrecording layer respectively, the first and second blank areas adjoiningthe first and second unused areas respectively. The computer programenables the computer system to further execute the steps of storing thegenerated positional information in a memory; recording an arbitraryinformation signal on the first unused area to change the first unusedarea to a used area; recording a predetermined signal on the first blankarea to change the first blank area to a used area after the arbitraryinformation signal is recorded on the first unused area; deleting thepositional information piece of the first blank area from the positionalinformation in the memory to update the positional information; andrecording the updated positional information on the predetermined areain the optical disc.

A seventh aspect of this invention provides an optical disc of one of arecordable type and a rewritable type for storing information which hasa plurality of recording layers including first and second recordinglayers, wherein a laser beam is applied to the second recording layerthrough a used area in the first recording layer to record arbitraryinformation on at least a part of the second recording layer, and theused area in the first recording layer has been used for at least one ofinformation recording and data recording, the optical disc having apredetermined area on which positional information is recorded, thepositional information being of a blank area in the second recordinglayer which occurs due to the presence of an unused area in the firstrecording layer, the blank area adjoining the unused area.

An eighth aspect of this invention is based on the seventh aspectthereof, and provides an optical disc wherein there is positionalinformation including positional information pieces of one or more blankareas inclusive of first and second blank areas in the second recordinglayer which occur due to the presence of first and second unused areasin the first recording layer respectively, the first and second blankareas adjoining the first and second unused areas respectively; thepositional information piece of the first blank area is deleted from thepositional information to update the positional information; and theupdated positional information is recorded on the predetermined area.

A ninth aspect of this invention is based on the first aspect thereof,and provides an apparatus wherein the third means comprises means forrecording the positional information sequentially on the recordinglayers in an order from a recording layer nearest an optical pickup to arecording layer farthest therefrom.

A tenth aspect of this invention is based on the third aspect thereof,and provides a method wherein the recording step comprises recording thegenerated positional information sequentially on the recording layers inan order from a recording layer nearest an optical pickup to a recordinglayer farthest therefrom.

An eleventh aspect of this invention is based on the fifth aspectthereof, and provides a computer program wherein the recording stepcomprises recording the generated positional information sequentially onthe recording layers in an order from a recording layer nearest anoptical pickup to a recording layer farthest therefrom.

A twelfth aspect of this invention is based on the seventh aspectthereof, and provides an optical disc wherein the positional informationis recorded sequentially on the recording layers in an order from arecording layer nearest an optical pickup to a recording layer farthesttherefrom.

This invention has advantages as follows. In this invention, an opticaldisc has a plurality of recording layers including first and secondrecording layers. A laser beam is applied to the second recording layerthrough a used area in the first recording layer to record arbitraryinformation on at least a part of the second recording layer. The usedarea in the first recording layer has been used for informationrecording. Positional information is generated. The generated positionalinformation is of a blank area in the second recording layer whichoccurs due to the presence of an unused area in the first recordinglayer. The blank area adjoins the unused area. The generated positionalinformation is recorded on a predetermined area in the optical disc. Thepositional information of the blank area is reproduced from thepredetermined area in the optical disc. The presence/absence of theblank area and the position of the blank area can be detected byreferring to the reproduced positional information. Therefore, at thetime of closing borders or finalizing the data recording on the opticaldisc, it is unnecessary to search for a blank area again. Accordingly, atime taken to close borders or finalize the data recording on theoptical disc can be shortened, and an enhanced convenience is available.

In this invention, positional information includes positionalinformation pieces of at least first and second blank areas in thesecond recording layer which occur due to the presence of first andsecond unused areas in the first recording layer respectively. The firstand second blank areas adjoin the first and second unused areasrespectively. A memory stores the positional information. An arbitraryinformation signal is recorded on the first unused area to change thefirst unused area to a used area. A predetermined signal is recorded onthe first blank area to change the first blank area to a used area afterthe arbitrary information signal is recorded on the first unused area.The positional information piece of the first blank area is deleted fromthe positional information in the memory to update the positionalinformation after the predetermined signal is recorded on the firstblank area. The updated positional information is recorded on thepredetermined area in the optical disc. Accordingly, blank areas in thelatest conditions can be accurately managed by referring to the updatedpositional information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a first prior-art DVD-R.

FIG. 2 is a diagram of a second prior-art DVD-R which is of a two-layersingle-sided type.

FIG. 3 is a sectional diagram of the second prior-art DVD-R, anobjective lens in an optical pickup, and a laser beam.

FIG. 4 is a sectional diagram of the second prior-art DVD-R which is ina first state.

FIG. 5 is a sectional diagram of the second prior-art DVD-R which is ina second state.

FIG. 6 is a block diagram of an information recording and reproducingsystem including a host apparatus, an optical-disc drive apparatus, andan optical disc according to a first embodiment of this invention.

FIG. 7 is a diagram of a sequence of instructions issued from the hostapparatus to the optical-disc drive apparatus in FIG. 6.

FIG. 8 is a sectional diagram of the optical disc in FIG. 6 which is ina state occurring at a first stage.

FIG. 9 is a sectional diagram of the optical disc in FIG. 6 which is ina state occurring at a second stage following the first stage.

FIG. 10 is a sectional diagram of the optical disc in FIG. 6 which is ina state occurring at a third stage following the second stage.

FIG. 11 is a sectional diagram of the optical disc in FIG. 6 which is ina state occurring at a fourth stage following the third stage.

FIG. 12 is a flowchart of a first portion of a control program for asystem controller in FIG. 6.

FIG. 13 is a flowchart of a second portion of the control program forthe system controller in FIG. 6.

FIG. 14 is a flowchart of a third portion of the control program for thesystem controller in FIG. 6.

FIG. 15 is a diagram of a blank-area table in a first state which isrepresented by management information stored in a data memory in FIG. 6and recorded on the optical disc in FIG. 6.

FIG. 16 is a diagram of the blank-area table in a second state.

FIG. 17 is a diagram of the blank-area table in a third state.

FIG. 18 is a sectional diagram of an optical disc in a second embodimentof this invention.

DETAILED DESCRIPTION OF THE INVENTION

Prior-art recording mediums and related prior-art drive apparatuses willbe explained below for a better understanding of this invention.

With reference to FIG. 1, a first prior-art DVD-R has a recording areadivided into an R-information area 401, a lead-in area 402, a data area403, and a lead-out area 404 which are successively arranged in thatorder as viewed in a radial direction from the inner circumferentialdisc edge toward the outer circumferential disc edge.

The R-information area 401 consists of a power calibration area (PCA)411 and a recording management area (RMA) 412. The PCA 411 extendsinward of the RMA 412. The data area 403 is assigned to user data. Thelead-in area 402 and the lead-out area 404 are used as buffers forabsorbing overruns of a recording and reproducing head (an opticalpickup) of a first prior-art disc drive apparatus. A border-in area anda border-out area or border-in areas and border-out areas in the dataarea 403 also serve as buffers for absorbing overruns of the recordingand reproducing head.

An outer portion of the lead-in area 402 which adjoins the data area 403is called an extra-border zone, and has a function similar to that ofthe border-in area. A portion of the data area 403 which is not clearlyreserved for data recording is called an invisible R-zone. In general,“R-zone” is also referred to as “Rzone”.

In FIG. 1, the reference numeral 421 denotes the extra-border zone, thedata area 403, and the lead-out area 404 which are in their statesoccurring when the DVD-R is virgin. The whole of the data area 403 formsthe invisible R-zone in the virgin DVD-R.

Contents data such as audio data representing one music tune, audiovisual data representing one drama, or computer data representing onefile can be recorded on the DVD-R. When a portion of the data area 403is reserved for contents data to be recorded, the head (the inner edge)of the invisible R-zone (Rzone) in the data area 403 is formed with anR-zone as denoted by the reference numeral 422 in FIG. 1. The contentsdata can be recorded on the R-zone from its starting edge (its inneredge). In the case where the size of the contents data is unknown, thecontents data can be recorded on the invisible R-zone from its startingedge (its inner edge).

To place a DVD-R having recorded contents data in a state where therecorded contents data can be reproduced by a first prior-art DVDplayer, it is necessary that an area to be mainly accessed and bufferareas located at the two sides of the area to be mainly accessed are setas used areas. This is because the first prior-art DVD player can notread out cutting information from a DVD-R, and uses only pit informationrecorded on a land of the DVD-R to reproduce recorded data from theDVD-R. When an unused area remains in a reserved R-zone, padding data of“0” is recorded on the unused area so that the unused area can berecognized as a used area. This procedure is referred as the closing ofan R-zone. In addition, as denoted by the reference numeral 423 in FIG.1, prescribed data is recorded on the extra-border zone and a border-outarea between which a bordered area, that is, a used R-zone, issandwiched. This procedure is referred as the closing of borders.

An area extending outward of and adjacently to the border-out area iskept empty as a border-in area for user data to be recorded next. Thus,as denoted by the reference numeral 423 in FIG. 1, an updated invisibleR-zone starts from a position immediately outward of the border-in area.The border-out area and the border-in area which are adjacent to eachother are collectively referred to as a border zone.

Contents data can be additionally recorded on the DVD-R. Specifically,as denoted by the reference numeral 424 in FIG. 1, the contents data isrecorded on the invisible R-zone from its starting edge (its inneredge). When the recording of all contents data on the DVD-R has beencompleted, prescribed data is recorded on the lead-out area 404 inaddition to performing the closing of the borders as denoted by thereference numeral 425 in FIG. 1. This procedure is referred to as thefinalization of the data recording on the DVD-R or simply thefinalization of the DVD-R. No more contents data can be additionallyrecorded on a DVD-R which has been finalized.

The recording management area (RMA) 412 is assigned to information formanaging changes in the recording states of the lead-in area 402, thedata area 403, and the lead-out area 404. The RMA 412 has an RMA lead-insection representing the start of the RMA 412, and a remaining sectionextending outward of the RMA lead-in section and assigned to recordingmanagement data (RMD). The RMA 412 is immediately preceded by a linkingloss area (LLA) which acts as a runway to establish PLL synchronizationor frame synchronization for data reproduction.

Regarding a DVD-R, a set of error correction code signals is calculatedfor every ECC block. The RMD in the RMA 412 is divided into segmentscorresponding to ECC blocks respectively. The RMD is managementinformation representing the recording state of the related DVD-R whichoccurs at the time of the recording of user data on the data area 403.For example, immediately before a DVD-R is ejected from the firstprior-art disc drive apparatus, signals representing the presentposition of each border zone and the present position of each R-zone arerecorded as an RMD block (RMD segment) on the DVD-R. RMD blocks (RMDsegments) in the RMA 412 are numbered #1, #2, . . . . There can be up to700 RMD blocks (RMD segments) in the RMA 412. The RMD blocks (RMDsegments) are successively arranged in the RMA 412 in a manner such thatthe newest RMD block (RMD segment) occupies a position nearest thelead-in area 402.

Thus, the RMD is essential information representing the recording stateof the related DVD-R. In the event that the RMD fails to be correctlyreproduced, it is difficult to additionally record contents data on theDVD-R. One way to enhance the reliability of RMD is disclosed inJapanese patent application publication number P2002-352522A(corresponding to U.S. patent application publication numberUS-2002-136134-A1).

FIG. 2 shows a second prior-art DVD-R which is of a two-layersingle-sided type. The prior-art DVD-R of FIG. 2 has a laminatedstructure including a first recording layer 501 and a second recordinglayer 502. The first recording layer 501 is closer to an optical pickup(a recording and reproducing head) of a second prior-art disc driveapparatus than the second recording layer 502 is.

The first recording layer 501 is divided into an R-information area 511,a lead-in area 512, a data area 513, and a middle area 514 which aresuccessively arranged in that order as viewed along a radial directionfrom the inner circumferential disc edge toward the outercircumferential disc edge. The second recording layer 502 is dividedinto an R-information area 521, a lead-out area 522, a data area 523,and a middle area 524 which are successively arranged in that order asviewed along a radial direction from the inner circumferential disc edgetoward the outer circumferential disc edge.

The first recording layer 501 in the prior-art DVD-R of FIG. 2 issimilar to the recording layer in the prior-art DVD-R of FIG. 1 exceptthat the middle area 514 replaces the lead-out area 404 (see FIG. 1).The second recording layer 502 is similar to the first recording layer501 except that the lead-out area 522 replaces the lead-in area 512. Thefirst recording layer 501 is scanned in a direction from the innercircumferential disc edge toward the outer circumferential disc edgeduring the recording of data thereon. The second recording layer 502 isscanned in a direction from the outer circumferential disc edge towardthe inner circumferential disc edge during the recording of datathereon.

With reference to FIG. 3, the optical pickup of the second prior-artdisc drive apparatus has an objective lens 602 through which a laserbeam 601 emitted from a light source in the optical pickup passes.During the recording of data on the second recording layer 502, theobjective lens 602 focuses the laser beam 601 on the second recordinglayer 502. In this case, the laser beam 601 passes through the objectivelens 602 and the first recording layer 501 before reaching the secondrecording layer 502. Thus, conditions of the recording of data on thesecond recording layer 502 depend on whether a portion of the firstrecording layer 501 through which the laser beam 601 passes is used orunused, that is, whether or not the portion of the first recording layer501 already has recorded data.

In the case where the laser beam 601 is controlled to always passthrough a used portion of the first recording layer 501 during therecording of data on the second recording layer 502, conditions of thedata recording can be constant. In this case, as shown in FIG. 3, thediameter of the laser beam 601 in the first recording layer 501 isgreater than that at the second recording layer 502. Therefore, a signalrecordable area in the second recording layer 502 is narrow relative toa used area in the first recording layer 501. The signal recordable areain the second recording layer 502 is narrower when errors (tolerance) inthe structures of the first and second recording layers 501 and 502 areconsidered.

FIG. 4 shows a prior-art signal recording procedure in which the laserbeam 601 is controlled to always pass through a used portion of thefirst recording layer 501 during the recording of data on the secondrecording layer 502.

With reference to FIG. 4, data is recorded on a first portion 1A of thefirst recording layer 501 while the first recording layer 501 is scannedalong a direction 701 from the inner circumferential disc side towardthe outer circumferential disc side. The data recording changes thefirst portion 1A of the first recording layer 501 to a used portion.Subsequently, data is recorded on a first portion 2B of the secondrecording layer 502 while the second recording layer 502 is scannedalong a direction 702 from the outer circumferential disc side towardthe inner circumferential disc side. The data recording changes thefirst portion 2B of the second recording layer 502 to a used portion.The first portion 2B of the second recording layer 502 is located abovethe first portion 1A of the first recording layer 501. During the datarecording on the first portion 2B of the second recording layer 502, thelaser beam continues to pass through the first portion 1A, that is, theused portion, of the first recording layer 501. The first portion 1A ofthe first recoding layer 501 and the first portion 2B of the secondrecording layer 502 constitute a used R-zone.

Thereafter, data is recorded on a second portion 3A of the firstrecording layer 501 while the first recording layer 501 is scanned alonga direction 703 from the inner circumferential disc side toward theouter circumferential disc side. The data recording changes the secondportion 3A of the first recording layer 501 to a used portion. Thesecond portion 3A of the first recording layer 501 is located outward ofthe first portion 1A thereof. There is an unused area in the firstrecording layer 501 between the first and second portions 1A and 3Athereof. Subsequently, data is recorded on a second portion 4B of thesecond recording layer 502 while the second recording layer 502 isscanned along a direction 704 from the outer circumferential disc sidetoward the inner circumferential disc side. The data recording changesthe second portion 4B of the second recording layer 502 to a usedportion. The second portion 4B of the second recording layer 502 islocated above the second portion 3A of the first recording layer 501.During the data recording on the second portion 4B of the secondrecording layer 502, the laser beam continues to pass through the secondportion 3A, that is, the used portion, of the first recording layer 501.The second portion 3A of the first recording layer 501 and the secondportion 4B of the second recording layer 502 constitute a used R-zone.

Thereafter, data is recorded on a third portion 5A of the firstrecording layer 501 while the first recording layer 501 is scanned alonga direction 705 from the inner circumferential disc side toward theouter circumferential disc side. The data recording changes the thirdportion 5A of the first recording layer 501 to a used portion. The thirdportion 5A of the first recording layer 501 is located immediatelyoutward of the second portion 3A thereof. Subsequently, data is recordedon a third portion 6B of the second recording layer 502 while the secondrecording layer 502 is scanned along a direction 706 from the outercircumferential disc side toward the inner circumferential disc side.The data recording changes the third portion 6B of the second recordinglayer 502 to a used portion. The third portion 6B of the secondrecording layer 502 is located above the second and third portions 3Aand 5A of the first recording layer 501. During the data recording onthe third portion 6B of the second recording layer 502, the laser beamcontinues to pass through one of the second and third portions 3A and5A, that is, the used portions, of the first recording layer 501. Thethird portion 5A of the first recording layer 501 and the third portion6B of the second recording layer 502 constitute a used R-zone.

With reference to FIG. 5, data is recorded on first portions of thefirst and second recording layers 501 and 502 to form a used R-zone 801,and then an R-zone 802 is reserved which extends immediately outward ofthe used R-zone 801, and which has second portions of the first andsecond recording layers 501 and 502. There is an invisible R-zone 803extending immediately outward of the reserved R-zone 802 and havingthird portions of the first and second recording layers 501 and 502.

In the case where data is recorded on only a part of the first recordinglayer 501 in the reserved R-zone 802 and hence an unused part remains inthe first recording layer 501 in the reserved R-zone 802, there occurs ablank area 804 in the second recording layer 502 between the reservedR-zone 802 and the invisible R-zone 803. The data recording on the blankarea 804 is allowed provided that the data recording on the firstrecording layer 501 in the reserved R-zone 802 and the invisible R-zone803 has been completed. This is because the laser beam is required toalways pass through a used portion of the first recording layer 501during the recording of data on any part of the second recording layer502. Thus, during the data recording on the invisible R-zone 803, theblank area 804 remains unaccessed.

The blank area 804 can not be handled in a way similar to the way ofhandling another R-zone for the following reasons 1) and 2).

1) The blank area 804 is narrow, and has only a small recordingcapacity. Therefore, in some cases, the blank area 804 can not provide adata area (CDA) having such a recorded information amount as to satisfya jump performance model which maintains the playback of informationeven during a seek time interval to implement the continuousreproduction of information. It should be noted that the informationplayed back during the seek time interval has been reproduced andmemorized immediately before the seek time interval. The jumpperformance model is indicated in, for example, unpublished documents“DVD Specifications for Rewritable/Re-recordable Discs Part 3: VIDEORECORDINGS, Version 1.9, September 1999, DVD Forum, VRX-G1”.

2) It is difficult to manage a timing at which data recording isallowed. As previously mentioned, the data recording on the blank area804 is allowed provided that the data recording on the first recordinglayer 501 in the reserved R-zone 802 and the invisible R-zone 803 hasbeen completed. Therefore, in almost all cases, padding data of “0” isrecorded on the blank area 804 at the time of the closing of borders, atthe time of the finalization of the DVD-R, or at a recordable timing. Itis conceivable to load the blank area 804 with computer data or videodata rather than the padding data.

Japanese patent application publication number P2002-352522A(corresponding to U.S. patent application publication numberUS-2002-136134-A1) discloses a typical prior-art apparatus for recordinginformation on a DVD-R. The prior-art apparatus in Japanese applicationP2002-352522A is designed for a DVD-R having only one recording layer.In an assumed case where the prior-art apparatus is applied to atwo-layer single-sided DVD-R, it may take a long time to search for ablank area at the time of closing a border in the DVD-R or finalizingthe data recording thereon.

First Embodiment

FIG. 6 shows an information recording and reproducing system including ahost apparatus 1, an optical-disc drive apparatus 2, and an optical disc3. The optical-disc drive apparatus 2 and the optical disc 3 are in afirst embodiment of this invention. The host apparatus 1 and theoptical-disc drive apparatus 2 are connected with each other. Theoptical disc 3 can be inserted into and ejected from the body of theoptical-disc drive apparatus 2.

The optical disc 3 is of a two-layer single-sided type. The optical disc3 uses a digital versatile disc recordable (DVD-R). The optical disc 3is formed with a central opening, and thus has an inner circumferentialedge in addition to an outer circumferential edge.

The host apparatus 1 includes, for example, a personal computer. Thehost apparatus 1 can instruct the optical-disc drive apparatus 2 torecord information on the optical disc 3 or reproduce informationtherefrom. It should be noted that the host apparatus 1 and theoptical-disc drive apparatus 2 may be located in a common casing. Forexample, the host apparatus 1 and the optical-disc drive apparatus 2 arecombined to form an optical-disc recorder or an optical-disc recordableplayer.

The optical-disc drive apparatus 2 has not only the function ofrecording information on the optical disc 3 but also the function ofreproducing information therefrom. The optical-disc drive apparatus 2includes a system controller 4, a recording and reproducing circuit 5, aprogram memory 6, a data memory 7, an internal bus 8, an optical pickup(a recording and reproducing head) 9, and an interface 10.

The system controller 4, the recording and reproducing circuit 5, thedata memory 7, and the interface 10 are bidirectionally connected by theinternal bus 8. The program memory 6 is connected with the systemcontroller 4. The optical pickup 9 is connected with the recording andreproducing circuit 5. The optical pickup 9 can optically access theoptical disc 3 which is placed at its normal position within the body ofthe optical-disc drive apparatus 2. The interface 10 is connected withthe host apparatus 1.

The system controller 4 includes a signal processor or a CPU. The systemcontroller 4 acts to control the whole of the optical-disc driveapparatus 2 according to a control program (a computer program). Therecording and reproducing circuit 5 implements writing and readinginformation in and from the optical disc 3 via the optical pickup 9. Theprogram memory 6 stores the control program for the system controller 4.Data to be recorded on the optical disc 3, data reproduced from theoptical disc 3, and management information can be written into and readout from the data memory 7, and temporarily stored therein. The opticalpickup 9 optically writes and reads data into and from the optical disc3 which is placed at its normal position within the body of theoptical-disc drive apparatus 2. The interface 10 connects the hostapparatus 1 and the internal bus 8.

The recording and reproducing circuit 5 implements writing and readingcontents information in and from the optical disc 3 via the opticalpickup 9. In addition, the recording and reproducing circuit 5implements writing and reading management information in and from theoptical disc 3 via the optical pickup 9. The system controller 4 writesand reads management information into and from the data memory 7 via theinternal bus 8. Furthermore, the system controller 4 controls therecording and reproducing circuit 5 to write and read managementinformation into and from R-information areas in the optical disc 3 viathe optical pickup 9.

The system controller 4, the recording and reproducing circuit 5, theprogram memory 6, the data memory 7, the internal bus 8, and theinterface 10 compose a computer system which operates according to thecontrol program stored in the program memory 6.

The optical disc 3 has the structure same as that in FIG. 2. Thus, theoptical disc 3 includes a laminate of a first recording layer 501 and asecond recording layer 502 (see FIG. 2). The first recording layer 501has an R-information area 511 (see FIG. 2). The second recording layer502 has an R-information area 521 (see FIG. 2). The R-information areas511 and 521 align axially with respect to the optical disc 3. Each ofthe R-information areas 511 and 521 includes a recording management area(RMA) assigned to recording management data (RMD). Recording managementdata is also referred to as management information. The RMD in each RMAis divided into segments corresponding to ECC blocks respectively. TheRMD blocks (RMD segments) are successively arranged in the RMA of theR-information area 511 in a manner such that the newest RMD block (RMDsegment) occupies an outermost position. The RMD blocks (RMD segments)are successively arranged in the RMA of the R-information area 521 in amanner such that the newest RMD block (RMD segment) occupies aninnermost position.

At a prescribed timing such as a timing immediately before the opticaldisc 3 is ejected from the body of the optical-disc drive apparatus 2,one ECC block of management information is recorded on the R-informationarea 511 (see FIG. 2) in the first recording layer 501 of the opticaldisc 3 while the R-information area 511 is scanned by the optical pickup9 along a direction from the inner circumferential disc edge toward theouter circumferential disc edge. It should be noted that one ECC blockconsists of 16 sectors. After the R-information area 511 has been fullyused, the R-information area 521 (see FIG. 2) in the second recordinglayer 502 of the optical disc 3 is used instead of the R-informationarea 511. Specifically, at a prescribed timing such as a timingimmediately before the optical disc 3 is ejected from the body of theoptical-disc drive apparatus 2, one ECC block of management informationis recorded on the R-information area 521 while the R-information area521 is scanned by the optical pickup 9 along a direction from the outercircumferential disc edge toward the inner circumferential disc edge.

With reference to FIG. 7, an example of instructions sequentially issuedfrom the host apparatus 1 to the optical-disc drive apparatus 2 includesan instruction S10 to reserve a new R-zone, an instruction S20 to closea second reserved R-zone, and an instruction S30 to close a firstreserved R-zone to implement the closing of borders. In general,“R-zone” is also referred to as “Rzone”. The instruction S30 may be tofinalize the data recording on the optical disc 3. The moment of theissue of the instruction S10 is prior to the moment of the issue of theinstruction S20. The moment of the issue of the instruction S20 is priorto the moment of the issue of the instruction S30.

With reference to FIG. 8, a used R-zone (Rzone) 100 is formed in thefirst recording layer 501 and the second recording layer 502 in the dataarea of the optical disc 3. The used R-zone means a data-recordedR-zone, that is, an R-zone having recorded data. In the case where thehost apparatus 1 issues the optical-disc drive apparatus 2 aninstruction to reserve a new R-zone (that is, the instruction S10 inFIG. 7), the optical-disc drive apparatus 2 operates as follows.

The system controller 4 in the optical-disc drive apparatus 2 receivesthe instruction to reserve a new R-zone from the host apparatus 1 viathe interface 10 and the internal bus 8. The system controller 4controls the optical pickup 9 via the internal bus 8 and the recordingand reproducing circuit 5 in response to the received instruction,thereby reading the newest RMD block (RMD segment) from the RMA in theR-information area 511 or 521 of the optical disc 3. The newest RMDblock (RMD segment) represents the position of the used R-zone 100.

In the case where RMD is stored only in the R-information area 511, anRMD block (RMD segment) at an outermost position is the newest one. Inthe case where RMD is stored in both the R-information areas 511 and521, an RMD block (RMD segment) at an innermost position in theR-information area 521 is the newest one.

Subsequently, the system controller 4 provides a first reserved R-zone101 a in an invisible R-zone of the optical disc 3 in response to thenewest RMD block (RMD segment). As shown in FIG. 8, the first reservedR-zone 101 a extends in a place outward of and adjacent to the usedR-zone 100.

As a result, there occurs a first blank area 103 a (see FIG. 8) in thesecond recording layer 502 of the optical disc 3. As shown in FIG. 8,the first blank area 103 a extends between the second recording layer502 defining the outer edge of the first reserved R-zone 101 a and thesecond recording layer 502 defining the inner edge of an invisibleR-zone 102 immediately outward of the first reserved R-zone 101 a. Datarecording on the first blank area 103 a is allowed provided that datarecording on the first recording layer 501 in the first reserved R-zone101 a and the invisible R-zone 102 has been completed. The first blankarea 103 a adjoins the first recording layer 501 in the first reservedR-zone 101 a and the invisible R-zone 102.

Then, the system controller 4 calculates the start sector number and theend sector number of the first blank area 103 a. The start sector numberand the end sector number mean the sector-based start address and thesector-based end address, respectively. The data memory 7 has a sectionassigned to RMD having pure RMD components and other componentsrepresenting a blank-area table. This section of the data memory 7 isreferred to as the RMD recording section. The system controller 4accesses the data memory 7, and adds the calculated start address numberand the calculated end address number of the first blank area 103 a tothe blank-area table to update the RMD in the data memory 7 and generatea new RMD block (RMD segment). The system controller 4 controls the datamemory 7 to send the updated RMD (the new RMD block or segment) to therecording and reproducing circuit 5. The system controller 4 controlsthe optical pickup 9 via the internal bus 8 and the recording andreproducing circuit 5, thereby writing the updated RMD (the new RMDblock or segment) into the RMA in the R-information area 511 or 521 ofthe optical disc 3.

FIG. 12 is a flowchart of a portion (a subroutine) of the controlprogram for the system controller 4 which relates to the above-mentionedoperation of the optical-disc drive apparatus 2.

With reference to FIG. 12, a first step S11 of the program portionreceives the instruction to reserve a new R-zone from the host apparatus1.

A step S12 following the step S11 controls the optical pickup 9 via theinternal bus 8 and the recording and reproducing circuit 5 in responseto the received instruction, thereby reading the newest RMD block (RMDsegment) from the RMA in the R-information area 511 or 521 of theoptical disc 3.

A step S13 subsequent to the step S12 provides a first reserved R-zone101 a in an invisible R-zone of the optical disc 3 in response to thenewest RMD block (RMD segment). As a result, there occurs a first blankarea 103 a (see FIG. 8) in the second recording layer 502 of the opticaldisc 3.

A step S14 following the step S13 calculates the start sector number andthe end sector number of the first blank area 103 a.

A step S15 subsequent to the step S14 accesses the data memory 7, andadds the calculated start address number and the calculated end addressnumber of the first blank area 103 a to the blank-area table to updatethe RMD in the data memory 7 and generate a new RMD block (RMD segment).The step S15 controls the data memory 7 to send the updated RMD (the newRMD block or segment) to the recording and reproducing circuit 5. Thestep S15 controls the optical pickup 9 via the internal bus 8 and therecording and reproducing circuit 5, thereby writing the updated RMD(the new RMD block or segment) into the RMA in the R-information area511 or 521 of the optical disc 3. After the step S15, the currentexecution cycle of the program portion ends and then the program returnsto a main routine.

It should be noted that the optical disc 3 may be ejected from the bodyof the optical-disc drive apparatus 2 after the writing of the updatedRMD into the optical disc 3.

FIG. 15 shows an example of the contents of the blank-area tableprovided in the data memory 7. As shown in FIG. 15, a 4-byte signalrepresenting the start sector number of the first blank area 103 a isstored in a field storage location 201 from a byte position of “N” to abyte position of “N+3” in the blank-area table. A 4-byte signalrepresenting the end sector number of the first blank area 103 a isstored in a field storage location 202 from a byte position of “N+4” toa byte position of “N+7” in the blank-area table. Other field storagelocations in the blank-area table are loaded with data of “0”.

With reference to FIG. 9, in the case where a certain amount of data isrecorded on the invisible R-zone 102 and then an R-zone is reserved, aused R-zone 104 is formed in the invisible R-zone 102 and a secondreserved R-zone 105 a and an invisible R-zone 106 are successivelyformed. The used R-zone 104 extends outward of and adjacently to thefirst reserved R-zone 101 a and the first blank area 103 a. The secondreserved R-zone 105 a extends outward of and adjacently to the usedR-zone 104. The invisible R-zone 106 extends outward of the secondreserved R-zone 105 a. In the first recording layer 501, the invisibleR-zone 106 adjoins the second reserved R-zone 105 a. In addition, thereis a second blank area 107 a in the second recording layer 502 of theoptical disc 3. The second blank area 107 a extends between the secondrecording layer 502 defining the outer edge of the second reservedR-zone 105 a and the second recording layer 502 defining the inner edgeof the invisible R-zone 106. Data recording on the second blank area 107a is allowed provided that data recording on the first recording layer501 in the second reserved R-zone 105 a and the invisible R-zone 106 hasbeen completed. The second blank area 107 a adjoins the first recordinglayer in the second reserved R-zone 105 a and the invisible R-zone 106.

In this case, the optical-disc drive apparatus 2 operates in a waysimilar to the previously-mentioned operation concerning the R-zonereservation to form the first reserved R-zone 101 a. Specifically, thesystem controller 4 calculates the start sector number and the endsector number of the second blank area 107 a. The system controller 4accesses the data memory 7, and adds the calculated start address numberand the calculated end address number of the second blank area 107 a tothe blank-area table to update the RMD in the data memory 7 and generatea new RMD block (RMD segment). The system controller 4 controls the datamemory 7 to send the updated RMD (the new RMD block or segment) to therecording and reproducing circuit 5. The system controller 4 controlsthe optical pickup 9 via the internal bus 8 and the recording andreproducing circuit 5, thereby writing the updated RMD (the new RMDblock or segment) into the RMA in the R-information area 511 or 521 ofthe optical disc 3.

FIG. 16 shows a related example of the contents of the blank-area tableprovided in the data memory 7. As shown in FIG. 16, a 4-byte signalrepresenting the start sector number of the second blank area 107 a isstored in a field storage location 203 from a byte position of “N+8” toa byte position of “N+1” in the blank-area table. A 4-byte signalrepresenting the end sector number of the second blank area 107 a isstored in a field storage location 204 from a byte position of “N+12” toa byte position of “N+15” in the blank-area table.

With reference to FIGS. 9 and 10, the optical-disc drive apparatus 2records a desired information signal (data) on a part of the secondreserved R-zone 105 a via the optical pickup 9. As a result, the secondreserved R-zone 105 a has an unused part. The unused part means a partwhich has not been used for data recording yet. The desired informationsignal may be recorded on the whole of the second reserved R-zone 105 a.In addition, the optical-disc drive apparatus 2 records data on a partof the invisible R-zone 106 to change the invisible R-zone 106 to anincomplete or invisible R-zone 108. In the case where the host apparatus1 issues the optical-disc drive apparatus 2 an instruction to close thesecond reserved R-zone 105 a (that is, the instruction S20 in FIG. 7),the optical-disc drive apparatus 2 implements the closing of the secondreserved R-zone 105 a. Specifically, the optical-disc drive apparatus 2writes padding data of “0” (that is, ineffective data) into the unusedpart of the second reserved R-zone 105 a. As a result, the secondreserved R-zone 105 a is closed, and changes to a used R-zone 105 b (seeFIG. 10).

In more detail, the system controller 4 in the optical-disc driveapparatus 2 receives the instruction to close the second reserved R-zone105 a from the host apparatus 1 via the interface 10 and the internalbus 8. The system controller 4 controls the optical pickup 9 via theinternal bus 8 and the recording and reproducing circuit 5 in responseto the received instruction, thereby reading the newest RMD block (RMDsegment) from the RMA in the R-information area 511 or 521 of theoptical disc 3.

Subsequently, the system controller 4 stores the read-out newest RMDblock (RMD segment) into the RMD recording section of the data memory 7.Then, the system controller 4 checks the blank-area table represented bythe newest RMD block (RMD segment) in the data memory 7 to decidewhether a blank area is present or absent which is allowed to be loadedwith data as a result of closing the second reserved R-zone 105 a.

Specifically, the system controller 4 decides the presence of the secondblank area 107 a which is allowed to be loaded with data as a result ofclosing the second reserved R-zone 105 a by the following actions A1,A2, and A3. A1: The system controller 4 recognizes the presence of thesecond blank area 107 a from the blank-area table. A2: The systemcontroller 4 ascertains the position of the used part of the firstrecording layer 501 in the incomplete or invisible R-zone 108. The usedpart means a data-recorded part, that is, a part having recorded data.A3: The system controller 4 ascertains that the whole of the firstrecording layer 501 in the second reserved R-zone 105 a has been usedfor data recording. Thereafter, the system controller 4 sends paddingdata of “0” (that is, ineffective data) to the recording and reproducingcircuit 5 and controls the optical pickup 9 via the internal bus 8 andthe recording and reproducing circuit 5, thereby writing the paddingdata of “0” into the second blank area 107 a in the optical disc 3.Thus, the second blank area 107 a changes to a used area 107 b as shownin FIG. 10.

Preferably, the system controller 4 refers to the RMD in the data memory7 to decide whether or not the second reserved R-zone 105 a has beenfully used for data recording, that is, whether or not the secondreserved R-zone 105 a has an unused part. The unused part means a partwhich has not been used for data recording yet. In the event that thesecond reserved R-zone 105 a has an unused part, the optical-disc driveapparatus 2 writes the padding data of “0” into the second blank area107 a after closing the second reserved R-zone 105 a.

In this case, the closing of the second reserved R-zone 105 a isperformed as follows. The system controller 4 sends padding data of “0”(that is, ineffective data) to the recording and reproducing circuit 5and controls the optical pickup 9 via the internal bus 8 and therecording and reproducing circuit 5, thereby writing the padding data of“0” into the unused part of the second reserved R-zone 105 a. As aresult, the second reserved R-zone 105 a is closed, and changes to aused R-zone 105 b (see FIG. 10). Subsequently, the system controller 4accesses the data memory 7, and refers to an unclosed-area listrepresented by the RMD therein. The system controller 4 deletes thesecond reserved R-zone 105 a from the unclosed-area list to update theRMD in the data memory 7 and generate a new RMD block (RMD segment). Thesystem controller 4 controls the data memory 7 to send the updated RMD(the new RMD block or segment) to the recording and reproducing circuit5. The system controller 4 controls the optical pickup 9 via theinternal bus 8 and the recording and reproducing circuit 5, therebywriting the updated RMD (the new RMD block or segment) into the RMA inthe R-information area 511 or 521 of the optical disc 3. The writing ofthe updated RMD (the new RMD block or segment) into the RMA may beomitted from this stage.

In the case where the first recording layer 501 in the invisible R-zone106 is fully unused, the second blank area 107 a is not allowed to beloaded with data as a result of closing the second reserved R-zone 105a.

Subsequently, the system controller 4 accesses the data memory 7, anddeletes the start address number and the end address number of thesecond blank area 107 a from the blank-area table and moves upinformation pieces representative of the start address number and theend address number of a later blank area (or later blank areas) in theblank-area table to update the RMD in the data memory 7 and generate anew RMD block (RMD segment). The system controller 4 writes data of “0”into the places in the blank-area table where the moved-up informationpieces originally exist. The system controller 4 controls the datamemory 7 to send the updated RMD (the new RMD block or segment) to therecording and reproducing circuit 5. The system controller 4 controlsthe optical pickup 9 via the internal bus 8 and the recording andreproducing circuit 5, thereby writing the updated RMD (the new RMDblock or segment) into the RMA in the R-information area 511 or 521 ofthe optical disc 3.

FIG. 13 is a flowchart of a portion (a subroutine) of the controlprogram for the system controller 4 which relates to the above-mentionedoperation of the optical-disc drive apparatus 2.

With reference to FIG. 13, a first step S21 of the program portionreceives the instruction to close the second reserved R-zone 105 a fromthe host apparatus 1.

A step S22 following the step S21 controls the optical pickup 9 via theinternal bus 8 and the recording and reproducing circuit 5 in responseto the received instruction, thereby reading the newest RMD block (RMDsegment) from the RMA in the R-information area 511 or 521 of theoptical disc 3. The step S22 stores the read-out newest RMD block (RMDsegment) into the RMD recording section of the data memory 7.

A step S23 subsequent to the step S22 searches the blank-area tablerepresented by the newest RMD block (RMD segment) in the data memory 7for a blank area which is allowed to be loaded with data as a result ofclosing the second reserved R-zone 105 a. Specifically, the step S23finds the second blank area 107 a which is allowed to be loaded withdata as a result of closing the second reserved R-zone 105 a.

A step S24 following the step S23 sends padding data of “0” (that is,ineffective data) to the recording and reproducing circuit 5 andcontrols the optical pickup 9 via the internal bus 8 and the recordingand reproducing circuit 5, thereby writing the padding data of “0” intothe second blank area 107 a in the optical disc 3. Thus, the secondblank area 107 a changes to a used area 107 b as shown in FIG. 10.

Preferably, the step S24 refers to the RMD in the data memory 7 todecide whether or not the second reserved R-zone 105 a has been fullyused for data recording, that is, whether or not the second reservedR-zone 105 a has an unused part. In the event that the second reservedR-zone 105 a has an unused part, the step S24 functions to write thepadding data of “0” into the second blank area 107 a after closing thesecond reserved R-zone 105 a.

In this case, the step S24 implements the closing of the second reservedR-zone 105 a as follows. The step S24 sends padding data of “0” (thatis, ineffective data) to the recording and reproducing circuit 5 andcontrols the optical pickup 9 via the internal bus 8 and the recordingand reproducing circuit 5, thereby writing the padding data of “0” intothe unused part of the second reserved R-zone 105 a. As a result, thesecond reserved R-zone 105 a is closed, and changes to a used R-zone 105b. Subsequently, the step S24 accesses the data memory 7, and refers tothe unclosed-area list represented by the RMD therein. The step S24deletes the second reserved R-zone 105 a from the unclosed-area list toupdate the RMD in the data memory 7 and generate a new RMD block (RMDsegment). The step S24 controls the data memory 7 to send the updatedRMD (the new RMD block or segment) to the recording and reproducingcircuit 5. The step S24 controls the optical pickup 9 via the internalbus 8 and the recording and reproducing circuit 5, thereby writing theupdated RMD (the new RMD block or segment) into the RMA in theR-information area 511 or 521 of the optical disc 3. The writing of theupdated RMD (the new RMD block or segment) into the RMA may be omittedfrom this stage.

A step S25 subsequent to the step S24 accesses the data memory 7, anddeletes the start address number and the end address number of thesecond blank area 107 a from the blank-area table and moves upinformation pieces representative of the start address number and theend address number of a later blank area (or later blank areas) in theblank-area table to update the RMD in the data memory 7 and generate anew RMD block (RMD segment). The step S25 writes data of “0” into theplaces in the blank-area table where the moved-up information piecesoriginally exist. The step S25 controls the data memory 7 to send theupdated RMD (the new RMD block or segment) to the recording andreproducing circuit 5. The step S25 controls the optical pickup 9 viathe internal bus 8 and the recording and reproducing circuit 5, therebywriting the updated RMD (the new RMD block or segment) into the RMA inthe R-information area 511 or 521 of the optical disc 3. After the stepS25, the current execution cycle of the program portion ends and thenthe program returns to the main routine.

FIG. 17 shows a related example of the contents of the blank-area tableprovided in the data memory 7. The 4-byte signal representing the startsector number of the second blank area 107 a and the 4-byte signalrepresenting the end sector number of the second blank area 107 a areabsent from the blank-area table. As shown in FIG. 17, a 4-byte signalrepresenting the start sector number of a third blank area is stored ina field storage location 205 from a byte position of “N+8” to a byteposition of “N+11” in the blank-area table. A 4-byte signal representingthe end sector number of the third blank area is stored in a fieldstorage location 206 from a byte position of “N+12” to a byte positionof “N+15” in the blank-area table. A 4-byte signal representing thestart sector number of a fourth blank area is stored in a field storagelocation 207 from a byte position of “N+16” to a byte position of “N+19”in the blank-area table. A 4-byte signal representing the end sectornumber of the fourth blank area is stored in a field storage location208 from a byte position of “N+20” to a byte position of “N+23” in theblank-area table. In the absence of the third and fourth blank areas,the field storage locations 205, 206, 207, and 208 are loaded with dataof “0”.

It is unnecessary to fill the second blank area 107 a with padding dataof “0” at the above-indicated timing. Other data may be recorded on thesecond blank area 107 a at a later timing. In this case, when the datarecording on the second blank area 107 a has been completed, the startaddress number and the end address number of the second blank area 107 aare deleted from the blank-area table and thus the RMD is updated. It isunnecessary to record other data on the whole of the second blank area107 a at one time. Other data may be recorded on only a part of thesecond blank area 107 a. In this case, the second blank area 107 aexcept the used part is newly registered in the RMD. Specifically, inthe blank-area table, the start sector number of the second blank area107 a or the end sector number thereof is updated.

Sometimes the optical disc 3 is ejected from the body of theoptical-disc drive apparatus 2 after the updated RMD is recorded on theRMA in the R-information area 511 or 521 of the optical disc 3. In thiscase, the optical-disc drive apparatus 2 will lose the RMD concerningthe present conditions of the optical disc 3. When the optical disc 3 isinserted into the body of the optical-disc drive apparatus 2 again, thenewest RMD block (RMD segment) is read out from the RMA in theR-information area 511 or 521 of the optical disc 3. The read-out RMDblock (RMD segment) is stored into the data memory 7. As a result, theoptical-disc drive apparatus 2 retrieves the RMD concerning the presentconditions of the optical disc 3.

In the case where the above-mentioned operation procedures are iteratedso that the recording of the desired information signal on the opticaldisc 3 is completed, the host apparatus 1 issues the optical-disc driveapparatus 2 an instruction to close the first reserved R-zone 101 a toimplement the closing of a border or an instruction to finalize the datarecording on the optical disc 3 (that is, the instruction S30 in FIG.7). In response to the instruction, the optical-disc drive apparatus 2operates as follows.

The system controller 4 in the optical-disc drive apparatus 2 receivesthe instruction to close the first reserved R-zone 101 a to implementthe closing of a border or the instruction to finalize the datarecording on the optical disc 3 from the host apparatus 1 via theinterface 10 and the internal bus 8. The system controller 4 controlsthe optical pickup 9 via the internal bus 8 and the recording andreproducing circuit 5 in response to the received instruction, therebyreading the newest RMD block (RMD segment) from the RMA in theR-information area 511 or 521 of the optical disc 3.

Subsequently, the system controller 4 stores the read-out newest RMDblock (RMD segment) into the RMD recording section of the data memory 7.Then, the system controller 4 checks the blank-area table represented bythe newest RMD block (RMD segment) in the data memory 7 to decidewhether a blank area is present or absent which is allowed to be loadedwith data as a result of closing the first reserved R-zone 101 a, andwhether or not a blank area is present in or absent from another portionof the optical disc 3.

Thereafter, the system controller 4 sends padding data of “0” (that is,ineffective data) to the recording and reproducing circuit 5 andcontrols the optical pickup 9 via the internal bus 8 and the recordingand reproducing circuit 5, thereby writing the padding data of “0” intothe first reserved R-zone 101 a in the optical disc 3. Subsequently, thesystem controller 4 accesses the data memory 7, and refers to anunclosed-area list represented by the RMD therein. The system controller4 deletes the first reserved R-zone 101 a from the unclosed-area list toupdate the RMD in the data memory 7 and generate a new RMD block (RMDsegment). The system controller 4 controls the data memory 7 to send theupdated RMD (the new RMD block or segment) to the recording andreproducing circuit 5. The system controller 4 controls the opticalpickup 9 via the internal bus 8 and the recording and reproducingcircuit 5, thereby writing the updated RMD (the new RMD block orsegment) into the RMA in the R-information area 511 or 521 of theoptical disc 3. The writing of the updated RMD (the new RMD block orsegment) into the RMA may be omitted from this stage. In this way, thefirst reserved R-zone 101 a is closed, and changes to a used R-zone 101b as shown in FIG. 11. Thus, the first recording layer 501 in the firstreserved R-zone 101 a has been fully used so that the first blank area103 a is now allowed to be loaded with data.

After the closing of the first reserved R-zone 101 a, the systemcontroller 4 sends padding data of “0” (that is, ineffective data) tothe recording and reproducing circuit 5 and controls the optical pickup9 via the internal bus 8 and the recording and reproducing circuit 5,thereby writing the padding data of “0” into the first blank area 103 ain the optical disc 3. Thus, the first blank area 103 a changes to aused area 103 b as shown in FIG. 11. When there is another blank area(or other blank areas) in the optical disc 3, the system controller 4operates to write the padding data of “0” into the blank area. In FIG.11, a used R-zone 109 originates from the incomplete or invisible R-zone108 (see FIG. 10), and is loaded with the desired information signal. Itis preferable to form a border-out area (not shown in FIG. 11) in aplace outward of the used R-zone 109 and to record prescribed data onthe border-out area.

Subsequently, the system controller 4 accesses the data memory 7, anddeletes the start address number and the end address number of the firstblank area 103 a from the blank-area table and moves up informationpieces representative of the start address number and the end addressnumber of a later blank area (or later blank areas) in the blank-areatable to update the RMD in the data memory 7 and generate a new RMDblock (RMD segment). The system controller 4 writes data of “0” into theplaces in the blank-are table where the moved-up information piecesoriginally exist. Also in the presence of the other blank area which isfilled with the padding data of “0” at this stage, the system controller4 deletes the start address number and the end address number of theother blank area from the blank-area table and moves up informationpieces representative of the start address number and the end addressnumber of a later blank area (or later blank areas) in the blank-areatable to update the RMD in the data memory 7 and generate a new RMDblock (RMD segment). The system controller 4 writes data of “0” into theplaces in the blank-area table where the moved-up information piecesoriginally exist.

Thereafter, the system controller 4 checks the blank-area table todetect whether the uppermost field storage location in the blank-areatable is filled with data of “0”. When the uppermost field storagelocation in the blank-area table is filled with data of “0”, the systemcontroller 4 decides the absence of any blank area from the optical disc3. Then, the system controller 4 controls the data memory 7 to send theupdated RMD (the new RMD block or segment) to the recording andreproducing circuit 5. The system controller 4 controls the opticalpickup 9 via the internal bus 8 and the recording and reproducingcircuit 5, thereby writing the updated RMD (the new RMD block orsegment) into the RMA in the R-information area 511 or 521 of theoptical disc 3.

FIG. 14 is a flowchart of a portion (a subroutine) of the controlprogram for the system controller 4 which relates to the above-mentionedoperation of the optical-disc drive apparatus 2.

With reference to FIG. 14, a first step S31 of the program portionreceives, from the host apparatus 1, the instruction to close the firstreserved R-zone 101 a to implement the closing of a border or theinstruction to finalize the data recording on the optical disc 3 fromthe host apparatus 1.

A step S32 following the step S31 controls the optical pickup 9 via theinternal bus 8 and the recording and reproducing circuit 5 in responseto the received instruction, thereby reading the newest RMD block (RMDsegment) from the RMA in the R-information area 511 or 521 of theoptical disc 3. The step S32 stores the read-out newest RMD block (RMDsegment) into the RMD recording section of the data memory 7.

A step S33 subsequent to the step S32 searches the blank-area tablerepresented by the newest RMD block (RMD segment) in the data memory 7for a blank area which is allowed to be loaded with data as a result ofclosing the first reserved R-zone 101 a, and for a blank area in anotherportion of the optical disc 3 or blank areas in other portions of theoptical disc 3. Specifically, the step S33 finds the first blank area103 a which is allowed to be loaded with data as a result of closing thefirst reserved R-zone 101 a.

A step S34 following the step S33 sends padding data of “0” (that is,ineffective data) to the recording and reproducing circuit 5 andcontrols the optical pickup 9 via the internal bus 8 and the recordingand reproducing circuit 5, thereby writing the padding data of “0” intothe first reserved R-zone 101 a in the optical disc 3. In this way, thefirst reserved R-zone 101 a is closed, and changes to a used R-zone 101b as shown in FIG. 11. Thus, the first recording layer 501 in the firstreserved R-zone 101 a has been fully used so that the first blank area103 a is now allowed to be loaded with data. After the closing of thefirst reserved R-zone 101 a, the step S34 sends padding data of “0”(that is, ineffective data) to the recording and reproducing circuit 5and controls the optical pickup 9 via the internal bus 8 and therecording and reproducing circuit 5, thereby writing the padding data of“0” into the first blank area 103 a in the optical disc 3. Thus, thefirst blank area 103 a changes to a used area 103 b as shown in FIG. 11.When there is another blank area (or other blank areas) in the opticaldisc 3, the step S34 functions to write the padding data of “0” into theblank area.

A step S35 subsequent to the step S34 accesses the data memory 7, anddeletes the start address number and the end address number of the firstblank area 103 a from the blank-area table and moves up informationpieces representative of the start address number and the end addressnumber of a later blank area (or later blank areas) in the blank-areatable to update the RMD in the data memory 7 and generate a new RMDblock (RMD segment). The step S35 writes data of “0” into the places inthe blank-area table where the moved-up information pieces originallyexist. Also in the presence of the other blank area which is filled withthe padding data of “0” at this stage, the step S35 deletes the startaddress number and the end address number of the other blank area fromthe blank-area table and moves up information pieces representative ofthe start address number and the end address number of a later blankarea (or later blank areas) in the blank-area table to update the RMD inthe data memory 7 and generate a new RMD block (RMD segment). The stepS35 writes data of “0” into the places in the blank-area table where themoved-up information pieces originally exist.

A step S36 following the step S35 checks the blank-area table to detectwhether the uppermost field storage location in the blank-area table isfilled with data of “0”. When the uppermost field storage location inthe blank-area table is filled with data of “0”, the step S36 decidesthe absence of any blank area from the optical disc 3. Then, the stepS36 controls the data memory 7 to send the updated RMD (the new RMDblock or segment) to the recording and reproducing circuit 5. The stepS36 controls the optical pickup 9 via the internal bus 8 and therecording and reproducing circuit 5, thereby writing the updated RMD(the new RMD block or segment) into the RMA in the R-information area511 or 521 of the optical disc 3. After the step S36, the currentexecution cycle of the program portion ends and then the program returnsto the main routine. On the other hand, when the uppermost field storagelocation in the blank-area table is not filled with data of “0”, thestep S36 decides the presence of at least one blank area in the opticaldisc 3. In this case, the program immediately exits from the step 36before returning to the main routine.

As described above, the start sector number and the end sector number ofeach blank area are registered in the RMD in the data memory 7. The RMDin the data memory 7 is updated in accordance with changes in theconditions of blank areas which include the presence/absence conditionsthereof and the positional conditions thereof. The updated RMD is sentfrom the data memory 7 before being recorded on the specified area inthe optical disc 3. Thus, it is possible to know the presence/absence ofa blank area and the position thereof by referring to the newest RMDread out from the specified area in the optical disc 3. Therefore, atthe time of closing a border or finalizing the data recording on theoptical disc 3, it is unnecessary to search for a blank area again.Accordingly, a time taken to close a border or finalize the datarecording on the optical disc 3 can be shortened, and the optical-discdrive apparatus 2 is very convenient.

Second Embodiment

A second embodiment of this invention is similar to the first embodimentthereof except for design changes described hereafter. The secondembodiment of this invention uses an optical disc 3A instead of theoptical disc 3. The optical disc 3A is of a two-layer single-sided type.The optical disc 3A uses a digital versatile disc recordable (DVD-R).

As shown in FIG. 18, the optical disc 3A includes a laminate of a firstrecording layer 501 and a second recording layer 502. A reserved R-zonecan be provided only in the first recording layer 501 of the opticaldisc 3A. A reserved R-zone can also be provided in both the first andsecond recording layers 501 of the optical disc 3A.

In the optical disc 3A of FIG. 18, a first reserved R-zone 301, a usedR-zone 302, a second reserved R-zone 304, and an incomplete (orinvisible) R-zone 306 are successively formed as viewed along adirection from the inner circumferential disc edge toward the outercircumferential disc edge. The first reserved R-zone 301 includeportions of both the first and second recording layers 501 and 502. Apart of the first recording layer 501 in the first reserved R-zone 301has been used for data recording. The remaining part of the firstrecording layer 501 in the first reserved R-zone 301, and the whole ofthe second recording layer 502 therein are unused. The used R-zone 302has portions of both the first and second recording layers 501 and 502which have been used for data recording. The second reserved R-zone 304has only a portion of the first recording layer 501. The whole of thesecond reserved R-zone 304 is unused. The incomplete (or invisible)R-zone 306 include portions of both the first and second recordinglayers 501 and 502. A part of the first recording layer 501 in theincomplete (or invisible) R-zone 306 has been used for data recording.

The first reserved R-zone 301, the used R-zone 302, the second reservedR-zone 304, and the incomplete (or invisible) R-zone 306 are givenR-zone numbers #10, #11, #12, and #13, respectively. There is managementinformation (RMD) in which the R-zone number of each R-zone is made intocorrespondence with a known sector number or numbers among the startsector number, the jump sector number, and the end sector number of theR-zone. The start sector number, the jump sector number, and the endsector number mean the sector-based start address, the sector-based jumpaddress, and the sector-based end address, respectively. The managementinformation is recorded on the RMA in the R-information area 511 or 521of the optical disc 3A. The management information is also stored in thedata memory 7 of the optical-disc drive apparatus 2.

Regarding the used R-zone 302, the start sector number, the jump sectornumber, and the end sector numbers are known. Regarding the incomplete(or invisible) R-zone 306 which has the used part, the start sectornumber and the end sector number ESNB are known. Regarding an invisibleR-zone which is fully unused, the end sector number and the jump sectornumber are undecided. Regarding a reserved R-zone (the second reservedR-zone 304) which has only a portion of the first recording layer 501,the jump sector number is absent.

In FIG. 18, the used R-zone 302 given the R-zone number #11 has thestart sector number XA, the jump sector number YA, and the end sectornumber ESNA. The start sector number XA is equal to the sector number ofa point from which the data recording on the used R-zone 302 is started.The jump sector number YA is equal to the sector number of a point inthe first recording layer 501 which is scanned immediately before thedata recording on the first recording layer 501 is replaced by the datarecording on the second recording layer 502 through a jumping process.The end sector number ESNA is equal to the sector number of a point atwhich the data recording on the used R-zone 302 is ended.

The optical disc 3A has prerecorded sync signals located at positionsspaced at prescribed intervals. Specifically, during the manufacture ofthe optical disc 3A, sync signals are recorded thereon by cutting. Thedata recording on the optical disc 3A is implemented on asector-by-sector basis while the positions of the sync signals aredetected and used as references for positional control of the datarecording.

Since only a part of the first recording layer 501 in the first reservedR-zone 301 has been used for data recording, there is a blank area 303formed by the second recording layer 502 between the first reservedR-zone 301 and the used R-zone 302. Since the second reserved R-zone 304which has only a portion of the first recording layer 501 is unused,there is a blank area 305 formed by the second recording layer 502between the used R-zone 302 and the incomplete (or invisible) R-zone306. The blank area 305 extends above the second reserved R-zone 304sandwiched between the used R-zone 302 and the incomplete (or invisible)R-zone 306.

The blank area 303 has an end sector number XB determined by the startsector number XA of the used R-zone 302. The start sector number of theblank area 303 is equal to the end sector number ESNA of the used R-zone302.

It is previously known that the diameter of the laser beam in the firstrecording layer 501 is greater than that at the second recording layer502. Accordingly, an area in the second recording layer 502 on which asignal can be recorded by the laser beam passing through a used area inthe first recording layer 501 is narrower than the used area in thefirst recording layer 501. Therefore, regarding the first reservedR-zone 301, the outer R-zone boundary at the second recording layer 502is located inward of the outer circumference of the first reservedR-zone 301 in the first recording layer 501. The position of the outerR-zone boundary at the second recording layer 502 corresponds to the endsector number XB of the blank area 303 while the position of the outercircumference of the first reserved R-zone 301 in the first recordinglayer 501 corresponds to the start sector number XA of the used R-zone302. On the other hand, regarding the used R-zone 302, the inner R-zoneboundary at the second recording layer 502 is located outward of theinner circumference of the used R-zone 302 in the first recording layer501. The position of the inner R-zone boundary at the second recordinglayer 502 corresponds to the end sector number ESNA of the used R-zone302 while the position of the inner circumference of the used R-zone 302in the first recording layer 501 corresponds to the start sector numberXA of the used R-zone 302. The end sector number XB of the blank area303 and the start sector number XA of the used R-zone 302 are in aprescribed relation. For example, the end sector number XB of the blankarea 303 is equal to a value resulting from bit inversion of the startsector number XA of the used R-zone 302. Thus, the end sector number XBof the blank area 303 and the start sector number XA of the used R-zone302 are in one-to-one correspondence. Therefore, the end sector numberXB of the blank area 303 is calculated from the start sector number XAof the used R-zone 302. The position at the end sector number ESNA ofthe used R-zone 302 depends on the on-disc radial position at the startsector number XA of the used R-zone 302, and is decided in view offactors including the difference in diameter between the laser beam inthe first recording layer 501 and the laser beam at the second recordinglayer 502.

The blank area 305 has an end sector number YB determined by the jumpsector number YA of the used R-zone 302. The start sector number of theblank area 305 is equal to the end sector number ESNB of the incomplete(or invisible) R-zone 306.

The end sector number YB of the blank area 305 and the jump sectornumber YA of the used R-zone 302 are in a relation similar to thatbetween the end sector number XB of the blank area 303 and the startsector number XA of the used R-zone 302. Accordingly, the end sectornumber YB of the blank area 305 is calculated from the jump sectornumber YA of the used R-zone 302 in a way similar to the calculation ofthe end sector number XB of the blank area 303 from the start sectornumber XA of the used R-zone 302.

To allow the blank areas 303 and 305 to be identified and detected,their start sector numbers and end sector numbers are registered in theRMD (the management information). The start sector numbers and the endsector numbers can be updated in accordance with changes of the blankareas 303 and 305.

As previously mentioned, in the management information, the R-zonenumber of each R-zone is made into correspondence with a known sectornumber or numbers among the start sector number, the jump sector number,and the end sector number of the R-zone. The management information isrecorded on the RMA in the R-information area 511 or 521 of the opticaldisc 3A. The management information is also stored in the data memory 7of the optical-disc drive apparatus 2. Accordingly, the blank areas 303and 305 can also be identified and detected in the case where the R-zonenumbers are registered in the management information and are suitablyupdated.

For example, the R-zone numbers #10 and #11 are designated with respectto the management information, and the corresponding sector numbersincluding the start sector number XA and the end sector number ESNArelated to the R-zone number #11 are derived from the managementinformation. It is detected or decided from the start sector number XAand the end sector number ESNA related to the R-zone number #11 thatthere is a blank area 303 having the start sector number ESNA and theend sector number XB and formed by the second recording layer 502between the R-zones having the R-zone numbers #10 and #11.

In addition, the R-zone numbers #11 and #13 are designated with respectto the management information, and the corresponding sector numbersincluding the jump sector number YA related to the R-zone number #11 andthe end sector number ESNB related to the R-zone number #13 are derivedfrom the management information. It is detected or decided from the jumpsector number YA related to the R-zone number #11 and the end sectornumber ESNB related to the R-zone number #13 that there is a blank area305 having the start sector number ESNB and the end sector number YB andformed by the second recording layer 502 between the R-zones having theR-zone numbers #11 and #13.

In the case where the incomplete (or invisible) R-zone 306 outward ofand adjacent to the second reserved R-zone 304 is fully unused, the endsector number of the incomplete R-zone 306 is undecided. Even in thiscase, it is detected or decided that there is a blank area 305 havingthe end sector number YB and formed by the second recording layer 502above the second reserved R-zone 304. Preferably, the start sectornumber of the blank area 305 is provisionally set to a prescribed value(for example, “0”). After data is recorded on at least a part of theincomplete (or invisible) R-zone 306 so that the end sector number ESNBof the incomplete R-zone 306 is decided, the start sector number of theblank area 305 is updated from the prescribed value to the value ESNB.

As understood from the above description, at least the end sector numberof each blank area is registered in the RMD in the data memory 7. TheRMD in the data memory 7 is updated in accordance with changes in theconditions of blank areas which include the presence/absence conditionsthereof and the positional conditions thereof. The updated RMD is sentfrom the data memory 7 before being recorded on the specified area inthe optical disc 3A. Thus, it is possible to know the presence/absenceof a blank area and the position thereof by referring to the newest RMDread out from the specified area in the optical disc 3A. Therefore, atthe time of closing borders or finalizing the data recording on theoptical disc 3A, it is unnecessary to search for a blank area again.Accordingly, a time taken to close borders or finalize the datarecording on the optical disc 3A can be shortened, and the optical-discdrive apparatus 2 is very convenient.

Third Embodiment

A third embodiment of this invention is similar to the first or secondembodiment thereof except that the optical disc 3 or 3A uses arewritable disc rather than a DVD-R. The number of times of recordingdata on a same area in the rewritable disc is relatively limited. Anexample of the rewritable disc is a digital versatile disc rewritable(DVD-RW).

In a virgin DVD-RW, both first and second recording layers are unused.Thus, during the first recording of data on a virgin DVD-RW, there mayoccur a blank area. Blank areas in a DVD-RW are processed as those in aDVD-R are.

Fourth Embodiment

A fourth embodiment of this invention is similar to the first or secondembodiment thereof except that the optical disc 3 or 3A uses athree-layer single-sided optical disc recordable or rewritable. Thethree-layer single-sided optical disc recordable or rewritable may bereplaced by a four-layer or more-layer single-sided optical discrecordable or writable. In addition, the three-layer single-sidedoptical disc recordable or rewritable may be replaced by an optical discrecordable or writable which has two or more recording layers at each ofthe two disc sides.

Fifth Embodiment

A fifth embodiment of this invention is similar to the first or secondembodiment thereof except for design changes described hereafter.

According to the fifth embodiment of this invention, the control programfor the system controller 4 is initially stored in a recording medium.The recording medium is connected with the optical-disc drive apparatus2 and is driven therein so that the control program is loaded from therecording medium into the program memory 6.

Alternatively, the control program may be downloaded to the programmemory 6 via a transmission line or a communication line.

1. An apparatus for recording information on an optical disc having aplurality of recording layers including first and second recordinglayers, the optical disc being of one of a recordable type and arewritable type, the apparatus comprising: first means for applying alaser beam to the second recording layer through a used area in thefirst recording layer to record arbitrary information on at least a partof the second recording layer, wherein the used area in the firstrecording layer has been used for at least one of information recordingand data recording; second means for generating positional informationof a blank area in the second recording layer which occurs due to thepresence of an unused area in the first recording layer, the blank areaadjoining the unused area; and third means for recording the positionalinformation generated by the second means on a predetermined area in theoptical disc.
 2. An apparatus as recited in claim 1, further comprising:fourth means provided in the second means for generating positionalinformation including positional information pieces of one or more blankareas inclusive of first and second blank areas in the second recordinglayer which occur due to the presence of first and second unused areasin the first recording layer respectively, the first and second blankareas adjoining the first and second unused areas respectively; a memoryfor storing the positional information generated by the fourth means;fifth means for recording an arbitrary information signal on the firstunused area to change the first unused area to a used area; sixth meansfor recording a predetermined signal on the first blank area to changethe first blank area to a used area after the fifth means records thearbitrary information signal on the first unused area; seventh means fordeleting the positional information piece of the first blank area fromthe positional information in the memory to update the positionalinformation; and eighth means for recording the updated positionalinformation generated by the seventh means on the predetermined area inthe optical disc.
 3. An apparatus as recited in claim 1, wherein thethird means comprises means for recording the positional informationsequentially on the recording layers in an order from a recording layernearest an optical pickup to a recording layer farthest therefrom.
 4. Amethod of recording information on an optical disc having a plurality ofrecording layers including first and second recording layers, theoptical disc being of one of a recordable type and a rewritable type,the method comprising the steps of: applying a laser beam to the secondrecording layer through a used area in the first recording layer torecord arbitrary information on at least a part of the second recordinglayer, wherein the used area in the first recording layer has been usedfor at least one of information recording and data recording; generatingpositional information of a blank area in the second recording layerwhich occurs due to the presence of an unused area in the firstrecording layer, the blank area adjoining the unused area; and recordingthe generated positional information on a predetermined area in theoptical disc.
 5. A method as recited in claim 4, wherein thepositional-information generating step comprises generating positionalinformation including positional information pieces of one or more blankareas inclusive of first and second blank areas in the second recordinglayer which occur due to the presence of first and second unused areasin the first recording layer respectively, the first and second blankareas adjoining the first and second unused areas respectively; themethod further comprising the steps of: storing the generated positionalinformation in a memory; recording an arbitrary information signal onthe first unused area to change the first unused area to a used area;recording a predetermined signal on the first blank area to change thefirst blank area to a used area after the arbitrary information signalis recorded on the first unused area; deleting the positionalinformation piece of the first blank area from the positionalinformation in the memory to update the positional information; andrecording the updated positional information on the predetermined areain the optical disc.
 6. A method as recited in claim 4, wherein therecording step comprises recording the generated positional informationsequentially on the recording layers in an order from a recording layernearest an optical pickup to a recording layer farthest therefrom.
 7. Acomputer system having a computer program that enables the computersystem to execute steps to record information on an optical disc havinga plurality of recording layers including first and second recordinglayers, the optical disc being of one of a recordable type and arewritable type, the computer system being enabled by the computerprogram to execute the steps of: applying a laser beam to the secondrecording layer through a used area in the first recording layer torecord arbitrary information on at least a part of the second recordinglayer, wherein the used area in the first recording layer has been usedfor at least one of information recording and data recording; generatingpositional information of a blank area in the second recording layerwhich occurs due to the presence of an unused area in the firstrecording layer, the blank area adjoining the unused area; and recordingthe generated positional information on a predetermined area in theoptical disc.
 8. A computer system as recited in claim 7, wherein thepositional-information generating step comprises generating positionalinformation including positional information pieces of one or more blankareas inclusive of first and second blank areas in the second recordinglayer which occur due to the presence of first and second unused areasin the first recording layer respectively, the first and second blankareas adjoining the first and second unused areas respectively; thecomputer system enabled by the computer program to further execute thesteps of: storing the generated positional information in a memory;recording an arbitrary information signal on the first unused area tochange the first unused area to a used area; recording a predeterminedsignal on the first blank area to change the first blank area to a usedarea after the arbitrary information signal is recorded on the firstunused area; deleting the positional information piece of the firstblank area from the positional information in the memory to update thepositional information; and recording the updated positional informationon the predetermined area in the optical disc.
 9. A computer system asrecited in claim 7, wherein the recording step comprises recording thegenerated positional information sequentially on the recording layers inan order from a recording layer nearest an optical pickup to a recordinglayer farthest therefrom.
 10. An optical disc of one of a recordabletype and a rewritable type for storing information which has a pluralityof recording layers including first and second recording layers, whereina laser beam is applied to the second recording layer through a usedarea in the first recording layer to record arbitrary information on atleast a part of the second recording layer, and the used area in thefirst recording layer has been used for at least one of informationrecording and data recording, the optical disc having a predeterminedarea on which positional information is recorded, the positionalinformation being of a blank area in the second recording layer whichoccurs due to the presence of an unused area in the first recordinglayer, the blank area adjoining the unused area.
 11. An optical disc asrecited in claim 10, wherein there is positional information includingpositional information pieces of one or more blank areas inclusive offirst and second blank areas in the second recording layer which occurdue to the presence of first and second unused areas in the firstrecording layer respectively, the first and second blank areas adjoiningthe first and second unused areas respectively; the positionalinformation piece of the first blank area is deleted from the positionalinformation to update the positional information; and the updatedpositional information is recorded on the predetermined area.
 12. Anoptical disc as recited in claim 10, wherein the positional informationis recorded sequentially on the recording layers in an order from arecording layer nearest an optical pickup to a recording layer farthesttherefrom.